1) Field of the Invention
The present invention relates to a four-light-type vehicle headlight including a first lamp unit and a second lamp unit, and more particularly, to a four-light-type vehicle headlight suitable for illuminating a road surface on outer side of a vehicle, when the vehicle makes a right or a left turn at an intersection or a corner, or when the vehicle travels on a curved road, such as an adaptive front-lighting system (AFS). In the specification, “road surface and the like” includes the road surface, and persons (pedestrians, etc.) and objects (other vehicles, traffic signs, buildings, etc.) on the road.
2) Description of the Related Art
A four-light-type vehicle headlight of this type is currently in use (see, for example, Japanese Patent Application Laid-Open Publication No. 2003-25906). The vehicle headlight in the earlier application will be explained first. Reference numerals in parenthesis correspond to those in the Japanese Patent Application Laid-Open Publication No. 2003-25906. A vehicle headlight (1) in the earlier application is a four-light-type vehicle headlight including a first lamp unit (3) and a second lamp unit (4). The first lamp unit (3) has a light source (8) and a reflector (5). The light source (8) has a first filament (15), a second filament (16), and a shade (11). The reflector (5) has a first reflection surface (6) and a second reflection surface (7). The second lamp unit (4) has a light source (10) and a reflector (9).
The action of the vehicle headlight in the earlier application will be explained below. When the first filament (15) of the light source (8) in the first lamp unit (3) is lighted, only a bending light-distribution-pattern (T1) is obtained. When the first filament (15) of the light source (8) in the first lamp unit (3) and the light source (10) in the second lamp unit (4) are lighted at the same time, the bending light-distribution-pattern (T1) and a low-beam light-distribution-pattern (P1) is obtained simultaneously. When the second filament (16) of the light source (8) in the first lamp unit (3) is lighted, bending light-distribution-patterns (T1, T2) and high-beam light-distribution-patterns (P0, P2) can be obtained simultaneously. When the light source (10) in the second lamp unit (4) is lighted, only the low-beam light-distribution-pattern (P1) is obtained.
In the vehicle headlight (1) in the earlier application, since the first lamp unit (3) has the function as a bending lamp and a function as a high-beam lamp, the bending lamp is not necessary, thereby having advantages in that the configuration becomes simple, the production cost is reduced, and an installation space for the bending lamp can be saved. The vehicle headlight (1) in the earlier application, however, has a problem in view of improvement both in the light distribution performance of the bending light-distribution-patterns (T1, T2) and in the light distribution performance of the high-beam light-distribution-patterns (P0, P2).